I've had my 24g nano up and running for almost 8 months. This past week I added 12 blue legged hermits. I'm seeing more empty shells now in the tank then I see shells with crabs in them. I've got one peppermint shrimp. Is that lil bastard eating my crabs?? Where else could they be going. Unless they are sucked so far inside thier shells I can't see them